EARNINGS

Union Pacific

Union Pacific Corp. said strong rail traffic and better results in its other businesses helped it post a profit of $128 million in the fourth quarter of 1984, compared to a loss of $22 million a year earlier.

For the full year, the railroad, energy, natural resources and land development company said its profit rose 66% to $494 million from $297 million in 1983. Revenue declined to $7.9 billion from $8.5 billion.

The profit was achieved despite a slight decline in revenue to $1.9 billion in the fourth quarter from $2 billion a year earlier, Union Pacific said.

William S. Cook, president and chief executive, said profit for the year was "the highest level ever achieved" by Union Pacific.